Final answer:
A differential interference contrast microscope would NOT be useful for a virologist to observe the surface features of virus particles since it is best for observing live cells, not the fine surface details of small particles like viruses.
Step-by-step explanation:
A virologist interested in observing the surface features of virus particles would find a transmission electron microscope (TEM) or a scanning electron microscope (SEM) particularly useful. However, among the microscopes listed, a differential interference contrast microscope would NOT be useful for her observations. This type of microscopy is more suited for observing live cells and the details within them but not the fine surface details of small particles such as viruses.
Virions, which are individual virus particles, are very small and typically range from 20 to 250 nanometers in diameter. Most virions are not visible under light microscopes, and traditionally, it was not until the electron microscope was developed that scientists could observe the structure of viruses in detail. For viewing surface structures specifically, SEM is very effective, while TEM is best for observing internal structures.
A confocal scanning laser microscope would be useful for viewing thick structures like biofilms, as opposed to surface details of virus particles. An atomic force microscope, while also not the primary choice for surface details, could offer some three-dimensional surface imaging. In contrast, in the case of differential interference contrast microscopy, its application is for live, unstained specimens and does not have the resolution required for studying the tiny, detailed surface features of viral particles. The scanning tunneling microscope, known for its applications in materials science at an atomic level, is also not typically used for biological virus surface imaging.